The glycolytic pathway is a fundamental anaerobic pathway for sugar metabolism in eukaryotic cells. Glycolysis has a dual role, to degrade sugars to generate energy (ATP) and to provide building blocks for synthetic reactions. The rate of conversion of glucose into pyruvate is regulated to meet these two major cellular needs. In particular, enzymes such as hexokinase, phosphofructokinase and pyruvate kinase, which catalyze irreversible reactions in the glycolytic process, are regulated as control points in glycolysis.
In 1930, Warburg pointed out that tumors have a high rate of anaerobic glycolysis and do not show a decreased glycolytic rate even at relatively high oxygen concentrations. This loss of regulatory control (i.e., the Pasteur effect) has come to be called the Warburg effect. Since then, subsequent studies have consistently corroborated the inherent nature of cancer to involve: a) rapid consumption of glucose; b) robust glycolytic activity (see Maublant et al., Bull Cancer, 85, 935-950 (1998)); c) rapid cell proliferation (see Chesney et al., Proc Natl Acad Sci USA, 96, 3047-3052 (1999)); d) production and accumulation of lactic acid (see Baggetto, Biochimie, 74, 959-974 (1992)); and e) a low extracellular pH with depleted glucose levels circumscribing the perimeter of the tumor. See U.S. Patent Application Publication No. 20060035981.
Due to cancer cells' metabolic shift to increased glycolytic flux for energy and production of macromolecule precursors, inhibition of glycolysis has emerged as a potential targeted anti-neoplastic strategy. Over the past several decades, various small molecules have been identified as possessing anti-tumor characteristics by acting through inhibition of the glycolytic pathway. Two in particular, 3-bromopyruvate (3-BrPA) and 2-deoxyglucose (2-DG), both of which target hexokinase, have been demonstrated to exhibit cytotoxicity towards transformed cells with mitochondrial respiratory defects or under hypoxia. See Xu et al., Cancer Res., 65, 613-621 (2005); Lui et al., Biochemistry, 40, 5542-5547 (2001); and Maher et al., Cancer Chemother. Pharmacol., 53, 116-122 (2004). The anti-neoplastic agent Imatinib (i.e., Gleevec®, Novartis Pharmaceuticals Incorporation, East Hanover, N.J., United States of America) has also been demonstrated to suppress hexokinase.
There remains a need for additional anti-cancer therapeutics, particularly those which target neoplastic cells via mechanisms related to the increased glycolytic flux associated with cancers. There also remains a need for additional methods of screening compounds to determine their ability to inhibit the enzymes associated with glycolysis.